Estimating, checking, and setting MEMLIMIT
The z/OS® MEMLIMIT parameter limits the amount of 64-bit (above-the-bar) storage that the CICS® address space can use. This storage includes the CICS dynamic storage areas above the bar (collectively called the GDSA) and MVS™ storage in the CICS region outside the GDSA.
About this task
CICS requires a MEMLIMIT value of 6 GB; any additional use by applications or JVMs should be allowed for with a larger value of MEMLIMIT. If you attempt to start a CICS region with a MEMLIMIT value that is less than 6 GB, message DFHSM0602 is issued, a system dump with the dump code KERNDUMP is produced, and CICS terminates.
You cannot alter the MEMLIMIT value for the CICS region while CICS is running. You can specify a new MEMLIMIT value on the next start of the CICS region.
CICS uses a different calculation to z/OS when checking MEMLIMIT to see whether a new GDSA extent can be allocated. CICS calculates the current usage as the amount that is allocated to the 64-bit Memory Objects, which includes both Usable and Hidden storage.